Apparatus for controlling the directional reception characteristics of loops or coil antenne



I Nov. 30 1926.

. 1,608,974 A. S. BLATTERMAN APPARATUS FOR CONTROLLING THE DIRECTIONAL RECEPTION CHARACTERISTICS OF LOOP OR COIL ANTENNAE Filed Jan. 26 1921 4 Sheets-Sheet 1 Mill ,xw awvamtoz Nov. 30 1926. 1,608,974

A. S. BLATTERMAN APPARATUS FOR- CONTROLLING THE DIRECTIONAL RECEPTION CHARACTERISTICS OF LOOP OR COIL ANTENNAE Fi-led Jan. 26. 192] 4 Sheets-Sheet 2 T mruc CoN we: son

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A. S. BLATTERMAN APPARATUS FOR CONTROLLING THE DIRECTIONAL RECEPTION CHARACTERISTICS OF LOOP OR COIL ANTENNAE I Filed Jan. 26. 1921 4 Sheets-Sheet 3 Nov. 30, 1926. 1,608,974

A. s. BLATTERMAN APPARATUS FOR CONTROLLING THE DIRECTIONAL RECEPTION CHARACTERISTICS OF LQOP OR COIL ANTENNAE Filed Jan. 26, 1921 4 Sheets-Sheet 4 MfiWMi vmtoz enema NW. ac, 192a res ltnithtt ll came;

ALBERT S. BLATTEBMAN, F VAIL, LITTLE SILVER, NEW JERQEY, ASSIGNQR W Hill'- RAD RADIO CQRPORATION, A CORPORATION OF DELAWARE.

AFPARATUS FOR CONTROLLING THE DIRECTIONAL HECJEIP'LION CHARAGTEMTIGS 0F LUOPS OR CGIL ANTENNEE.

Application filed. January 28, 1921. Serial Elle. 440,106.

Thisinvention relates to apparatus for controlling the directional reception characteristics of loop or coil antennae.

An object of this inventionis to provide 6 improved means for determining the direc tion of reception of radio communication.

provide improved means for altering the directional receiving characteristics so as to minimize the normal directional property of the receiving loop or coil and permit reception to substantially equal degree from all directions. I

A further object of the invention is to provide means for determining the sense or absolute direction of reception.

A feature of the present invention is the use of a metallic structure usually in the form of a harp or grid of parallel wires elect trically connected to one another and either grounded or connected to the receiving set. Such metallic structuremay be in the form of substantially parallelly arranged wires mounted on an insulating frame and electrically connected to one another through the lead wire connecting such parallel wires to ground or to the receiving set. Other forms of such metallic structure may be employed as pointed out more particularly hereinafter. Y 1

With the use of such metallic structure atmospheric disturbances or other disturbing eiiects due to trees, buildings, metal structures are largely eliminated and the determination of direction of reception is accom lished more readily and more accurate y.

The use of such metallic structure also enables the asymmetry of the reception characteristics to be enhanced for the purpose of determining the absolute direction or sense of the distant transmitter.

Further features and objects of the invention will be more fully understood from 50 the following detailed description and the accompanying drawings, in which Fig. ,1 is a perspective view showlng one electrically non-conducting material.

form of grid of wires serving as a metallic structure and embodying my invention;

Figs. 2, 3 and 4 are similar views of three :tliiferent modifications of such metallic struc- Fig. file a diagrammatic view showing a form of my metallic structure employed with a vertically arranged radio receiving loop;

Figs. ti and 7 are diagrammatic views similar to Fig. showing modifications;

Fig; 8 is a diagrammatic view showing a form of my double-pole, double-throw switch in connection with the receiving set whereby the loop terminals may nected in reversed relation thereto;

. Fig. 9 is a diagrammatic view showing another form of my metallic structure and a modified arrangement of connection with the receiving set;

Figs. 10, l1, l2 and 13 and let are diagrams showing the symmetry and asymmetry of directional receiving characteristics;

Figs. 15 and 16 are respectively diagrammatic side and end views showing one form of arrangement of a loop receiving antenna and a vacuum tube receiving set, combined with a form of my metallic structure.

As w ll appear more fully hereinafter, this invention is directed particularly to the use of an untuned metallic structure electrically related to a loop receiving antenna system for increasing the sharpness of its directional receiving characteristic. Such metallic structure, I have discovered, may take the form which may be described as a harp or as a grid of substantially electrically parallel conducting wires, electrically connected with one another and suitably grounded. In Fig. 1 l have shown such metallic structure as comprising a single set of wires 20 strung at their respective ends from the oppos'ite'end members 2' 22, of a substantially rectangular frame, formed of wood or like rigid,

side members of such non-conducting frame are indicated at 23, 24; These wires 20 are electrically connected to one another by means of the cross wire 25 and the ground wire indicated at 26 is shown in this instance connected directly to the cross wire 25.

lnFig. 2, I have shown two sets of parallelly arranged wires designated respective- The tilibe con- 1y 27, 28 and similarly mounted to be strung within the frame formed of the end members 21, 22, and side members 23, 24. The wires of the set 27 are connected to one another by means of the cross wire 29 and v grounded through the ground wire 30 and tween the up planeof the wires 43 is of the order of from' metry or asymmetry. i

' stantial the set of wires 28 are connected to one another by means of the cross wire 31 and rounded throu h the ground wire 32. hese sets of wires 27, 28 are shown disposed as one set 27 at the right in the frame and the other set 28 at the left in the frame.

In Fig. 3, I have shown a similar frame 21,.

22, 23, 24 of wood 0 the like, and two sets of wires, the sets of wires being arranged alternately within the frame. The set of wires33 are connected to one another by the cross wire 34 and grounded through the ground Wire 35, whereas the other set of wires 36is connected together by means of the cross wire 37 and grounded through the ground wire 38. r

In Fig. 4 I have shown a further modification of harp or grid of parallel wires in the form'of a rectangular spiral, theinner- -most portion being'indicated at 40 and the outermost portion at 41,. and suitably grounded through the ground wire 42 as byconnection with the innermost turn 40. Such spiral 40, 41 may be supported in a -similar manner on a framework of woodor other insulating material, as by two diagonally crossing supporting arms, as will be understood.

any of the forms set forth in the revious fig ures and I indicate at 43 a'set 0 such parallelly arranged wires and'at 44a cross connecting wire and at 45 the ground wire shown diagrammatically grounded at 46. The loop.

recelvm antenna is indicated at .47 in dash line an its terminal wires at 48, 49, connected in any approved manner to an approved type of receiving set,- employing a vacuum tube or other type of detector.

In Fig. 5 such receiving loop 47 is positioned substantially vertically whereas the set of parallelwires 43 is positioned suby horizontally. In the discoveries which I have made, the usual clearance. be-

r wire portion 50' and the a fraction of an inch to a few inches, de-

- pendent upon the particular e receiver loop employed, and they desired (1 gree of sym- In Fig. 6 I'have shown the use of my invention with a loop receiving antenna 51 disposed substantially vertically, of substantially rectangular formation but arranged to havethe angle 52 ofasuch rectangular loop atthe uppermost \apex, and the grid or har' of wires 43 is positioned substantially horizontally and connected by the grlound In Fig. 5, Ihave shown diagrammatically a harp or grid of parallel wires 4 arranged in.

wire 45 to ground at 46. The terminals '48,

49 of the loop 51 are connected to the terminals of the receiving set in the usual manner.

If desired, the grid 43 may be positioned below the apex 52 of the loop 51, in which position the plane of the loop 51 is between" the wires 43 of the'grid.

In Fig. 7, I- have shown a similar type of vertically disposed substantially rectangular form of loop antenna,51 having its apex disposed at 52 and the harp or'gr'id of parallel.

wires are arranged in two planeswithout the horizontal, one set of wires 53 being substantially parallel to one another and sub-- stantially parallel to the side wires' 54 of the rectangular loop 51 and perpendicular to the lane of the fOflI' sides of the rectangular oop 51 and the other set of wires 55 substantially arallel to one another and also substantial y parallel to the side wires 56/;

In Fig. 9-, I have hown a harp or grid f parallelly arranged comprisin two sets wires similar to that shown in Fig. 2 aforesaid, one set of wires being indicated in Fig. 9 as 80 and connected to one another by the wire 81, and grounded through the conductor 82 and the other set of wires is indicated at 83 connected together by the cross wire 84 andzgrounded through the conductor 85. The rectangular receiving. loop is indicated at 47 similar as aforesaid and its terminal wires 48, 49 connected to receiver terminals 61, 63. r

provided with the switch 86 for connectin and disconnecting with the conductor 8 leading to ground --88, and the ground wire 85 is provided with the switch 89-for con-v nection and disconnection with the conductor 90 leading to'the receiver terminal 61. In this arrapgement I have-\also shown switch 91 ,for co eating and disconnecting the two ground conductors .82, 85. with one, another.

t In the use of this embodiment of invention, for the purpose of listening in for stations, switches 91 and 89 are closed and the switch 86. opened whereby the two sets of wires 80, 83 are connected with-the receiving set which is thereby rendered highly sensitive in non-directional reception, that is to say, signals will be heard almost equally well from all directions'without the neces- Ian 1 However, in Fig. 9, the ground wire 82. is

. nooae'ra sity of rotating the loop. After the desired signals have been intercepted, using this connection the switch 91 is then opened, whereby the set of wires 83 solely are connected with the receiver set. Thereupon, the loop 4:7 is rotated until the strength of reception parison of the relative strengths of reception with the loop in the last-named position and in the position obtained when rotated 180 degrees in azimuth from same.

In lieu of rotating the loop through 180 degrees azimuth, a double pole, double throw reversing switch may be provided for the loop terminals 48 and 49 on one side of the switch and the receiver terminals 61, 03 on the other side, whereby the loop terminals may be connected in reversed relation to the receiving set. For this arrangement, as shown in Fig. 8, one side of the loop is marked head and the other side tail. Direction of transmitting station is deter- -mined by throwing the reversing switch pointing to the tail of the arrow, the transmitter is in the direction of the tail of the loop. lit the strongest signal is received with the switch in the position of the head of the arrow, marked on the switch, the sta- %ion is in the direction of the head of the oop.

Having now determined the sense of the direction of the distant transmitter, the switch is opened and switches 86 and 91 are closed, whereby both sets of wires 83, 80 of the grid are directly grounded through the ground wire 87 and without the receiver set, whereby the directional characteristics of the system are greatly intensified and made more symmetrical, so that the accurate bearing of the distant transmitter may 1 be taken.

l have represented in Fig. 10, the intensity of received energy plotted in polar coordinates for different angular positions of the plane of the loop, the origin being indicated at 100 and the different planes being measured in a counterclockwise direction from the axislOl, 102 as indicated. Thus,

' received energy for any particular plane represented by the angle 102, 100, 103, the intensity of the from a given station in line with the axis 101, 102, at a given intensity of trannnission is represented by the length of the radius vector 104. The right hand lobe shown in the form of a circle 105 having its left hand extremity of diameter at 100, represents substantially perfect symmetry of the reception characteristic for different positions from to +909, whereas the lett'hand lobe 106 also a circle, having its left hand diametrical value as 101.

right hand extremity of diameter at represents substantially perfect symmetry of the reception characteristic for diflerent positions of the plane of the loop antenna from 90 to 270.

; Such circles, and 106, as shown with equal diameters and tangent to one another at the polar origin 100, indicate perfect-synr metry of the entire system in respect to directional reception characteristics.

However, in practice with an ordinary loop antenna, the energy of rece tion for difl'erent positions of the plane 0 the loop is distorted and particularly distorted for the values proximate 90 and 270, i. e, where the plane of the loop is substantially at right angles to the direction of propagation of the received radio waves. In Fig. 11 l have plotted similarly in polar coordinates the reception characteristics tor different positions of the loop and designated the polar origin at 100, the extreme right hand diametrical value as 102 and the extrgne 1stortion or asymmetry as usually encountered principally with an ordinary loop antenna arranged and operated as heretofore proposed, is encountered at the location represented by the curved portion 107, for a range of position adjacent the values of 90, and by the curved portion 108 for the values in advance of and following the proximate value of 270. As will be noted the distortion represented by the curved portion 107 is of greater relative magnituoe than the distortion represented by the curved portion 108. lit will be noted that the diametrical value 100-102 ofthe right hand lobe 109 is less than the diametrical value 100-101 of the left hand lobe .110, and that as disclosed hereinabove, in Figs. 5, 6, 7 and also in Fig. 9, when switches 91 and 86 are closed and switch '89 is opened, the curve representing the reception characteristic corresponds to that shownin Fig. 12, plotted similarly in polar coordinates having the origin at 100; The resulting two lobesv 111 and 112 are or substantiallyduplicate and substantially symmetrical formation, the sole distortion being of relatively small value and closely proximate the values 90 and. 270.

The formot the two lobes 111 and 112 results by reason of the combination of the grid or harp ot parallelly arranged wires and the loop antenna, coacting generally upon the detector or other radio receiving means of the receiving set.

In the normal operation of an ordinary grid or harp oi wires arranged and operated Furthermore, these two zones of silence proximate respectively to the 90 and 270 ositions of the loop are not 180 apart rom one another thereby rendering it impossible to take a bearing on a distant transmitter with precision.

By my invention, as is indicated in Fig. 12, the zones of silence are restricted to the much closer limits indicated by tlle'llllliting vectors 100 125, and 100--l26, proximate the 99 position, and by the vectors 100-127 and 100128 proximate to the 270 position, and substantially 180 apart in position. And, if a zone of silence is not obtained but only a minimum of signal strength, the minima are more sharply dcfined as compared with those obtained with an ordinary loop, and substantially of equal intensity, as indicated by the vectors 100 113 and 100-129. Accordingly, my invention enables the bearing of the distant transmitter to be taken with precision.

In a similar manner, I have plotted in Fig. 13 to similar polar coordinates the form of the curves showing intensity of reception for different positions of plane of the loopwith the arrangement shown in Fig. 9, under the condition of having the switches '91 and 89 1n closed position and the switch 86in open a position, as hereinabove described. In such switches )1 and 89 closed and the' switch 86 open the intensity of. the received energy for arrangement and manner of connection the curve of reception characteristics is nearly that of a circle comprising the curved portlon 115 to the right of the vertical line 116, 117, and thecurved portion 118 to the left of the vertical line 116, 117,

Practically speaking, the distortions of the curves 115 and 118 relative to a complete circle, are negligible and accordingly with the-arrangement as shown in Fig: 9 with the difierent positions of the loop antenna remains substantially constant and of maximum value. r

With the arrangement shown in Fig; 9, however with the switches 91 and 86 open and the switch 89 closed, the intensity of reception for different positions of the loop corresponds to that shown by the curves in Fig. 14, where the origin is indicated at 100 and the right hand extreme diameter is indicated at 102 and the left hand extreme tic of the ordinary loop is enhanced by'the.

particular use-of my invention as described, thereby enabling the operator to determine the sense of the direction of the distant transmitter.

i In Figs. 15 and 16, I have shown diagrammatically a practical form of apparatus embodying my invention and combmm 11151111- plcr form the varlousinstrumenta ities set forth severally in the foregoing figures. I

have indicated at 130 a set of parallelly arranged, substantially horizontally disposed wires, shown in side view in Fig. 15 and in end view in Fig. 16. One such grid employed by me contained seventeen such wires, each six feet long and spaced two inches from one another and mounted in a wooden frame, similarly .as described hereinabove.

I have discussed the entire matter of the directional characteristics of loop antennae and associated shielding harp or grid of wires in my paper before the Franklin Institute, entitled, Theory and practical attainment in, the design and use of radio direction finding apparatus using closed c011 antenna, which appeared in the Journal of the Franklin Institute, volume 188, No. 3, September, 1919. t

The loop antenna indicated at 131 was Hi this case of the usual, square solenoidal type having a measurement of five feet on each side and containing six turns of- No. 18 B: & S. gauge wire, spaced axially three eighth. of an inch apart, mounted on a suitable frame in vertical position, the upper wireportions 132 and-lower wire portions 133 being substantially horizontal and the two side wire portions 134 and 135 belng substantially vertical... Such loop and the wire grid above described are practical for the reception of'wave lengths of the order of 750 meters and-"for such wave length, the distance between the plane of the wire 130 andthe plane of the wires 132 is most preferably three quarters of an inch. The'wires are connected together by the cross wire 136 similar as hereinabove described and the conductor 137 leads from the cross wire 136 to the switch 138, comprising the movable contact connector 139 and the two contact points 140 and 141.

The lead 142 connects the contact point 140 with one terminal 143 of the loop 131v and with the terminal 144 of the receiver set 145. The contact point 141is connected bythe ground wire 146 to ground indicated art-147. The other-terminal 148 of the loop 131 is connected by the lead 149 to the terminal 150 of the receiver set 145.

correspond to those shownin Fig. 9 and like reference numbers are employed to indi cate the same. It will be understood that theparticular parts for the particular type of receiver set is determined by the order of the wave length received. the intensity of the received waves and other iactors well known to those skilled/in the art. Q

Upon closing the contact connector 139 i of the switch 138 with its contact point 140' 1 the grid element 130, 136 is c nnected electrically directly with the grid 6 of the-vacuum tube receiver 64, whereby the apparatus is rendered substantially uniformly sensitive for the reception of waves for all positions of the loop and thereby the intensity of the re-' ceived energy is at a maximummnd obviates any adjustment of position of the loop antenna. This condition corresponds to the curve shown in Fig. 13.

Upon connecting the contact connector 139 of the switch 138 with the contact point 141, the grid element 130136 is connected directly to ground at 147 and the apparatus as a whole is rendered highly sensitive for direction finding, the direction of the transmitting station being readily determined .audibly through the telephone 79 in the usual manner. The relative-intensity of re- 'ceived energy for difierent positions of the plane ot the loop 131 corresponds to the rela- V tive energy intensity values shown in Fig. 12.

Iclaim: 1. Areceiving system'comprising in combination with a loop antenna and, a receiver set in radio reception, of means for controlling the directional properties of the receiving system and comprising two sets of wires,

disposed substantia ly parallel to one another and closely adjacent the loop antenna, a: conductor interconnecting each set of said parallelly arranged wiresand means for 0p- -tionall connecting and disconnecting both- ,sets 0 said parallel wires simultaneously withone another and with said receiver set, or simultaneously with one another and The various parts of the receiver set 145 ing and disconnecting 2. The combination with a loop antenna and 'areceiver. set in radio reception, of means for producing an azimuthal reception characteristic of the system consisting of substantially two tangent circles for the purpose of givmg sharp minima and symmetrical directional effect for different positions of the loop antenna, and comprising a plurality of sets of conductors disposed substantially parallel to a portion of said loop antenna and closely adjacent thereto for the purpose of producing a substantial shielding effect of the said loop antenna by said plurality of conductors, a conductor inter connecting said plurality of conductors and said last named conductor connected to the ground, and means for optionally connecting and disconnecting both sets of said parallel wires with one another and ground,

or only one of said sets of .parallel wires with said receiver set, the other set of wires being in this instance entirely disconnected.

3. A device for controlling the directional characteristics of a radio receiver, comprising a combination of a 100 antenna and a plurality of sets of parallel y arranged conductors, said conductors being of substantially equal length and arranged closely adjac'ent to a portion of said loop antenna to provide an electrical shield t9 said .loop antenna, and means for optionally connectboth sets of said parallel conductors with one another and gr0und,. 0r only one set of said sets of parallel conductors with said receiver, the other setof conductors being in this instance ontirely disconnected. I

4. Av device for controlling the directional characteristics of a radio receiver comprising a combination of a loop antenna and a plurality of sets of parallelly arranged wires arranged closely adjacent to said loop' antenna to provide an electrical shield thereto, a wire electrically interconnecting said set of wires and a conductor connected to said interconnecting wire, and means for optionally connecting and disconnecting both sets of said parallel wires with one another and ground, or only one ofsaid sets of parallel wires with said receiver set, the other set of wires being in this instance entirely disconnected.

In testimony whereof I afiix my signaground, or onl one of said sets of parallel ,ture.

wires with sai receiver setthe other vset of wires being entirely disconnected.

ALBERT S. BLATTERMAN. 

